With increasing traffic demand, radio networks are more frequently experiencing high load, either in the transport network or over the air interface. The increasing load in the networks may result in users requesting differentiation based on e.g. which type of subscription a user holds. As a consequence, it may be desirable for the network operators to provide differentiation in Quality of Service (QoS) between different user subscription types in a radio environment where limitations in bandwidth are experienced. This differentiation is commonly attained by providing different QoS to different users. Currently, the QoS measure is primarily implemented as relative bit rates, i.e. different subscriber types are provided differentiated bit rates, which has as an effect that users sharing the same network bottleneck at least from an average perspective shall experience differentiated bit rates governed by their subscription types. Thus, the users are graded according to an order of priority stipulated by the subscription type of the respective user. These subscription types may be graded as for example Gold, Silver and Bronze subscriptions, and their target QoS weights may be exemplified as 4, 2 and 1, respectively. This implies that the intention of the network operator is that a Gold user shall have twice the bit rate of a Silver user and four times that of a Bronze user over some period of time, given that all other conditions are the same for the different users.
Network throughput can be severely reduced due to limitations in the radio transceiver of a single user or if the user has a radio transceiver which consumes a great deal of the resources shared with other users. Examples of such resources are base station transmission power in the case of downlink transmission over the air interface, and shared bandwidth in the transport network. The network throughput may further be severely reduced in a situation where terminals are physically far from the base station, as the relative cost for providing a remote terminal with a given QoS is higher the further away the terminal is. Limitations may also occur in transport of data between Radio Network Controller (RNC) and NodeB.
Field studies show that actual relative bit rate for a user heavily depends on circumstances that are difficult or even impossible for the network operator to control, such as long term radio environment of a user. Field measurements have shown that the relative bit rate sometimes is higher than targeted for a user in a “good” radio environment. In the transport network, the relative bit rate may for example depend on the number of concurrent Transmission Control Protocol (TCP) flows that a user utilizes. Further, with the exemplified subscription types, the choice of assigning a particular bit rate to a user does not only dependent on the current subscription type, but also who has experienced a relatively low bit rate recently and thus should be prioritized and scheduled for transmission.
In practice, since the actual QoS of a user is dependent on numerous factors other than the current subscription type, it is thus difficult for a network operator to specify a policy in the form of target QoS weights and corresponding relative bit rates that in fact is conformed with. To conclude, these circumstances lead to the problem that a user with a subscription stipulating a higher priority than that of another user, for example a Gold user versus a Bronze user, still may experience a lower bit rate than that of the lower priority user, even though channel conditions are the similar for the two users which is a highly unwanted network behaviour.